Blenders have a limited amount of power that can be used to rotate the blades of such blenders in a blending medium. Generally, the blending medium includes both liquids and solids, and the purpose of a blender blade is to homogeneously mix the blending medium provided in a blender pitcher. A blender blade is configured to rotate about an axis of rotation, and normally includes two wings extending in opposite directions from a center portion. The leading edges of the wings are provided with cutting edges, and the wings are oriented at compound angles with respect to the center portion to provide the blender blade with a compound angle of attack.
As the blender blade rotates within the blending medium, the cutting edges define a cutting path, and the wings generate flow of the blending medium. Such flow can be characterized as a vortex which is used to blend the disseparate components of the blending medium together. The flow generated by the wings due to rotation of the blender blade draws the blending medium through the cutting path to homogeneously mix the blending medium, and grind any solids entrained therein using the cutting blades. For example, if the wings are twisted such that the leading edges are vertically oriented above the trailing edges, then rotation of the blender blade repeatedly draws the blending medium (including the solids) through the cutting path. As such, the rotation of the blender blade continuously draws the solids downwardly through the cutting path, and thereafter, pushes the solids upwardly along the interior surfaces of the blender pitcher. Consequently, the blending medium is homogeneously mixed because the solids are continually ground and mixed with remainder of the blending medium through rotation of the blender blade.
Because there is a limited amount of power available from commercial or household electrical receptacles, the efficiency of the blender blades is determined by the blender blades ability to generate flow to homogeneously mix the blending medium using the limited power available.
Oftentimes, the configurations of blender blades have inherent tradeoffs embodied therein. For example, to increase the amount of lift imparted on the blending medium, and increase the ability of a blender blade to draw the blending medium through the cutting path, the wings can be specially configured. As discussed above, the wings are typically oriented at compound angles with respect to the center portion to provide the blender blade with a compound angle of attack. As such, each of the wings is twisted such that its leading edge is vertically oriented above its trailing edge, and angled such that its distal end is vertically oriented above the center portion. Up to a threshold, the greater the angles of the wings, and, most importantly, the twists of the wings, the greater the amount of lift associated with the blender blade.
However, increasing lift produces a tradeoff because a greater amount of viscous resistance is generated when the twists and angles of the wings are increased. For example, a greater amount of blending medium impacts the bottom portions of the wings when the wings are twisted and angled as such. The more viscous resistance generated by impact of the blending medium on the bottom portions of the wings, the more drag which is imparted on the blender blade. Drag decreases the efficiency of the blender blade by decreasing the amount of flow generated thereby given the limited amount of power available. As such, the amount of lift generated by the blender blade is directly related to the amount of drag imparted on the blender blade, and therefore, is directly related to the amount of flow generated.
Consequently, there is a need to configure blender blades to optimize the relationship of lift and drag to efficiently generate flow. Such blender blades should have wings configured to decrease drag by decreasing the amount of impact provided by the wings on a blending medium, but, simultaneously, have dimensions which provide such blender blades with more than adequate lift.